1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus for forming an image on a recording material.
2. Description of the Related Art
Recently, a further speedup has been required of the electrophotographic image forming apparatus such as a printer, a facsimile, or a copying machine. Generally, as the speed up progresses, along with increase of a temperature of a fixing device, a rotational speed of a driving unit or an increase of used current due to increase of a size of a substrate of power source, temperature in the image forming apparatus tends to increase. When the temperature in the interior of the image forming apparatus increases, in turn, a temperature around a cartridge that includes a photosensitive drum (image bearing member), a development unit, and a cleaning unit increases. Temperature of members themselves in the cartridge tends to perform self temperature rise by the speed up.
Japanese Patent Application Laid-Open No. 2008-268528 discusses a technique for cooling the cartridge in order to prevent problems such as an image forming failure caused by melting of toner in the cartridge, which occurs due to the temperature increase around the cartridge or the temperature increase of itself.
In the configuration discussed in Japanese Patent Application Laid-Open No. 2008-268528, the cartridge is cooled by forming an air supplying path in a space between cartridges and sending air through this air supplying path. However, the formation of such an air supplying path between the cartridges necessitates securing of a certain amount of space for the air path between the cartridges, consequently inviting growing in size of the apparatus. Further, there is room for improvement from the viewpoint of cooling efficiency.
Accordingly, from the viewpoint of suppressing the growing in size of the apparatus and/or the cooling efficiency, not the space between the cartridges but a space through which a laser light beam for exposing the photosensitive drum included in the cartridge passes may be used as an air supplying path. However, when the space through which the laser light beam for exposing the photosensitive drum passes is used as the air supplying path, air flows along the surface of the photosensitive drum, creating a possibility of disturbance of a toner image on the photosensitive drum by the air. As a result, a wind velocity or the like is to be limited to prevent disturbance of the toner image, and there is a limit to a cooling capacity.